RFR: Cleanup ProcessTool.createJavaProcessBuilder()

[Chris Plummer]

Two issues (discovered by Alex):

1. A number of the "if" blocks are already covered by the `doubleWordArgs` loop.
2. The `doubleWordArgs` loop should exit with a `break` instead of a `continue`

-------------

Commit messages:
 - Cleanup ProcessTool.createJavaProcessBuilder()

Changes: https://git.openjdk.java.net/loom/pull/152/files
 Webrev: https://webrevs.openjdk.java.net/?repo=loom&pr=152&range=00
  Stats: 16 lines in 1 file changed: 0 ins; 15 del; 1 mod
  Patch: https://git.openjdk.java.net/loom/pull/152.diff
  Fetch: git fetch https://git.openjdk.java.net/loom pull/152/head:pull/152

PR: https://git.openjdk.java.net/loom/pull/152